Here is a list of all the postings Jim Nic has made in our forums. Click on a thread name to jump to the thread.
|Thread: double acting oscillating cylinder engine|
Thanks for the info Geoff, I'll have a look for the drawing. If I decide to make it I'll drop you a message regarding the cylinder.
That is indeed looking good.
I haven't got a double acting oscillator, neither have I got my next project lined up. This engine could well be my answer to both requirements. May I ask where you got the drawings from?
|Thread: Thomas from Hornby|
|Thread: The Workshop Progress Thread 2019|
Thanks for fixing my link Jason.
The engine is, as you say, a bit tight at the moment so will definitely ease a bit with more running. Also as it stands the cylinders and valve chest have no sealing so putting that in will reduce the air leakage and help. Another thing is that one of the return connecting rods is binding on the crank web which is the horrible clunking noise which can be heard which can't be helping with smooth running. There is plenty of work still to do to sort it before I even think about paint but since I haven't got my next project lined up that's not a problem.
Got the Overcrank running and it is as good as I'd hoped for with plenty of action going on with even more to come when the governor (yet to be made) is fitted.
It runs smoothly at an air pressure of 5psi (my metrification does not extend to pressure) but does not like going under about 100 RPM at the moment. There is an annoyoing knock/rubbing noise which is coming from one of the return connecting rods which will have to be sorted. I know what the problem is but haven't looked in to a solution yet.
There should be a link to Utoob here but it hasn't appeared. I'll try to get it sorted.
Edited By JasonB on 12/06/2019 06:57:22
Ouch! Hope all goes well for you.
Geoff. The valves are conventional slide type.
Ian. The con rod centre portion was from a piece of steel into which I made a centre hole and tapped stud holes in each end.
I then made a dead centre to avoid using a lathe dog on the part I needed to work.
The centre part of the rod was then machined between centres with a rounded tool to give a good finish and radiused corners.
The brass bearings are made in the time honoured fashion of soft soldering two bits of brass together, drilling the requisite size hole for the crankshaft on the join line and then machining the joined piece to size and shape before melting the soft solder to give a split bearing.
Thanks George, it's coming along.
What are you doing in hospital?
More progress on Stew Hart's Overcrank engine. I looked at the connecting rod design and decided I preferred a different type of bearing arrangement closer to the original on the only picture I have of the full size engine at Quarry Bank Mill.
This is what I ended up with:
With those made I have enough parts of the basic engine to get it to run.
The next step is to fettle and adjust everything until it is a runner then I can turn my attention to the governor.
The governor, a posh wooden base and a coat of paint should keep me occupied for a while yet.
|Thread: Extreme turning|
Well it's on there right enough, Eric, how did you get a tool to it?
|Thread: Hobbymat MD200|
For one thing, as has oft been said on here in response to the "What lathe?" question, you can make small parts on a big lathe but not big parts on a small lathe.
|Thread: stamford show vandals|
Words fail me at the utter mindlessness of such destruction.
How do you motivate yourself to rebuild a layout after that and if you did I cannot imagine it would be shown in public for the enjoyment of others again.
May the culprits be severely punished, but I doubt that that will happen.
|Thread: Adjustable workshop perching stool|
Looks very useful Stew, is that a lavatory seat you have on it? I manage with an assortment of 3 stools but not having the kit or expertise to weld I shall have to continue doing so.
|Thread: Pressure gauge help needed please.|
If you want something fairly quick there is always Jason's Jowitt engine, the complications being the shape of the cylinder block and the need to make the poppet valves and the spoked flywheels.
More complex is the Corliss type engine, free plans from Model Engine Makers website. Complications are the operation of the valves and making the flywheel. Everything else should be a breeze for you.
My last suggestion depends on your budget. The Eastern & Anderson Grasshopper model from a castings set available from Polly Models for about £240 I believe.
Hope this has given you something to consider
|Thread: The Chocolate Fireguard as designed by Mercedes Benz|
My Honda Jazz has a similar speed limit recognition system to Keith's Merc but has a display of the limit recognised by the camera. When I bought the car I thought it might be useful to have a reminder of what the limit was always on display in this day and age when limits change seemingly on a whim many times on most stretches of apparently similar road. However the display turns off after a minute or so of the car recognising a speed sign so there is no lasting reminder.
Even worse, the system can be set so that if the car recognises a speed limit sign it will not accelerate to a speed faster than that limit, which would be sensible if the car's camera and computer always correctly recognised the signs which is a long way from being the case.
The whole system has been turned off (after a lengthy trawl through a maze of menus).
Edited By Jim Nic on 26/04/2019 10:41:38
|Thread: The Workshop Progress Thread 2019|
In my last post on the progress of Stew Hart's Overcrank design I had made the valve eccentrics (and the eccentric straps) which had to be fitted to the crankshaft centre section before assembling the shaft. I then thought that making up the shaft would naturally be the next operation. When I came to cut the 12mm dia bar to length for the main part I found that the exact length depended on the width of the flywheel and the output pulley hubs. Sooo the next task was to obtain a flywheel casting from Stuart Models and machine it and make a pulley and, while I was at it, a pulley for the governer belt.
Then I assembled the crankshaft using my usual Loctite method but since this was a twin cylinder engine I also pinned the webs. The pins are fitted through the webs from one end, go through both the "big end" and the shaft section but stop short of protruding from the other end of the web.
And here is an assembly shot of the crankshaft in position before I had cut out the redundant pieces between the webs.
Next up I get to fit the laser cut crank return rods
|Thread: Potty overcrank|
Well there's this one
|Thread: Scaling dimensions|
I scaled up this Mogens Kilde designed Double Diagonal engine by two by simply doubling the drawing dimensions and found that while most aspects looked OK at twice design size, the fasteners most definitely did not. Bigger - yes, but not twice as big. I actually used BA fastenings instead of the metric called for on the drawings and just chose sizes I thought would look right and took the view that for an air powered model whatever I chose would would be strong enough.
Edited By Jim Nic on 25/03/2019 22:04:23
|Thread: The Workshop Progress Thread 2019|
I’ve not been well for a couple of months so there has been less progress on the Overcrank engine than normal.
This is the first engine I have built without the benefit of a build log or construction notes for guidance. My plan was to make the crankshaft next but luckily I had a close look at the drawings before I did and found that the valve eccentrics and crank centre bearing were on the shaft between the 2 throws.
The bearing could have been made as a split shell but I couldn’t see how to make the eccentric sheaves work with a join in them. So the only way seemed to me to make them as normal
and assemble them on the crankshaft before assembling and pinning the journals.
Happy days, the valves seem to move as they should so now it's back to the plan and build the crankshaft.
|Thread: Use of Colour on Drawings|
Firstly thanks for your consideration for the needs of your "customers".
My difficulty is sometimes visualising the shape of the part from the drawing so the addition of an occasional 3D image is welcome. The rendering of the intended result is also useful so I know where I am headed.
My preference of your options would be 1 or 2. Dimensioned in metric, on uncluttered A4 sheets in PDF format.
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